Allow FreeRTOS to ::printf (#1195)

The stdin/stdout FILEs have an internal mutex which needs to be initted
to a FreeRTOS one, or any sketch with ::printf will hang.  Automatically
create and acquire/release the shadowed mutex.

Requires new build of pico-quick-toolchain to function properly.  Tested
on preliminary local build.

Author: earlephilhower

cores/rp2040/_freertos.cpp

@@ -28,7 +28,7 @@ typedef struct {
 } FMMap;
 
 static FMMap *_map = nullptr;
-extern "C" SemaphoreHandle_t __get_freertos_mutex_for_ptr(mutex_t *m) {
+SemaphoreHandle_t __get_freertos_mutex_for_ptr(mutex_t *m, bool recursive) {
     if (!_map) {
         _map = (FMMap *)calloc(sizeof(FMMap), 16);
     }
@@ -42,7 +42,12 @@ extern "C" SemaphoreHandle_t __get_freertos_mutex_for_ptr(mutex_t *m) {
     for (int i = 0; i < 16; i++) {
         if (_map[i].src == nullptr) {
             // Make a new mutex
-            SemaphoreHandle_t fm = __freertos_mutex_create();
+            SemaphoreHandle_t fm;
+            if (recursive) {
+                fm = _freertos_recursive_mutex_create();
+            } else {
+                fm = __freertos_mutex_create();
+            }
             if (fm == nullptr) {
                 return nullptr;
             }

cores/rp2040/_freertos.h

@@ -59,8 +59,8 @@ extern "C" {
     extern void vTaskPreemptionEnable(TaskHandle_t p) __attribute__((weak));
 #endif
 
-    extern SemaphoreHandle_t __get_freertos_mutex_for_ptr(mutex_t *m);
 }
+extern SemaphoreHandle_t __get_freertos_mutex_for_ptr(mutex_t *m, bool recursive = false);
 
 // Halt the FreeRTOS PendSV task switching magic
 extern "C" int __holdUpPendSV;

cores/rp2040/lock.cpp

@@ -80,7 +80,7 @@ static SemaphoreHandle_t __getFreeRTOSMutex(_LOCK_T lock) {
     } else if (l == &__lock___arc4random_mutex) {
         return __lock___arc4random_mutex_freertos;
     }
-    return nullptr;
+    return __get_freertos_mutex_for_ptr(l, false);
 }
 
 static SemaphoreHandle_t __getFreeRTOSRecursiveMutex(_LOCK_T lock) {
@@ -96,20 +96,32 @@ static SemaphoreHandle_t __getFreeRTOSRecursiveMutex(_LOCK_T lock) {
     } else if (l == &__lock___env_recursive_mutex) {
         return __lock___env_recursive_mutex_freertos;
     }
-    return nullptr;
+    return __get_freertos_mutex_for_ptr((mutex_t *)l, true);
 }
 
 void __retarget_lock_init(_LOCK_T *lock) {
     if (__freeRTOSinitted) {
-        /* Already done in initFreeRTOSMutexes() */
+        mutex_t *l = (mutex_t *)lock;
+        if ((l == &__lock___at_quick_exit_mutex) || (l == &__lock___tz_mutex) || (l == &__lock___dd_hash_mutex) || (l == &__lock___arc4random_mutex)) {
+            /* Already done in initFreeRTOSMutexes() */
+        } else {
+            // Will init the mutex as well
+            __get_freertos_mutex_for_ptr(l, false);
+        }
     } else {
         mutex_init((mutex_t*) lock);
     }
 }
 
 void __retarget_lock_init_recursive(_LOCK_T *lock) {
     if (__freeRTOSinitted) {
-        /* Already done in initFreeRTOSMutexes() */
+        recursive_mutex_t *l = (recursive_mutex_t *)lock;
+        if ((l == &__lock___sinit_recursive_mutex) || (l == &__lock___sfp_recursive_mutex) || (l == &__lock___atexit_recursive_mutex) || (l == &__lock___malloc_recursive_mutex) || (l == &__lock___env_recursive_mutex)) {
+            /* Already done in initFreeRTOSMutexes() */
+        } else {
+            // Will init the mutex as well
+            __get_freertos_mutex_for_ptr((mutex_t *)l, true);
+        }
     } else {
         recursive_mutex_init((recursive_mutex_t*) lock);
     }